/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.mock.web;

import org.springframework.lang.Nullable;
import org.springframework.util.Assert;

import javax.servlet.*;
import java.io.IOException;

/**
 * Implementation of the {@link javax.servlet.FilterConfig} interface which
 * simply passes the call through to a given Filter/FilterChain combination
 * (indicating the next Filter in the chain along with the FilterChain that it is
 * supposed to work on) or to a given Servlet (indicating the end of the chain).
 *
 * @author Juergen Hoeller
 * @see javax.servlet.Filter
 * @see javax.servlet.Servlet
 * @see MockFilterChain
 * @since 2.0.3
 */
public class PassThroughFilterChain implements FilterChain {

    @Nullable
    private Filter filter;

    @Nullable
    private FilterChain nextFilterChain;

    @Nullable
    private Servlet servlet;


    /**
     * Create a new PassThroughFilterChain that delegates to the given Filter,
     * calling it with the given FilterChain.
     *
     * @param filter          the Filter to delegate to
     * @param nextFilterChain the FilterChain to use for that next Filter
     */
    public PassThroughFilterChain(Filter filter, FilterChain nextFilterChain) {
        Assert.notNull(filter, "Filter must not be null");
        Assert.notNull(nextFilterChain, "'FilterChain must not be null");
        this.filter = filter;
        this.nextFilterChain = nextFilterChain;
    }

    /**
     * Create a new PassThroughFilterChain that delegates to the given Servlet.
     *
     * @param servlet the Servlet to delegate to
     */
    public PassThroughFilterChain(Servlet servlet) {
        Assert.notNull(servlet, "Servlet must not be null");
        this.servlet = servlet;
    }


    /**
     * Pass the call on to the Filter/Servlet.
     */
    @Override
    public void doFilter(ServletRequest request, ServletResponse response) throws ServletException, IOException {
        if (this.filter != null) {
            this.filter.doFilter(request, response, this.nextFilterChain);
        }
        else {
            Assert.state(this.servlet != null, "Neither a Filter not a Servlet set");
            this.servlet.service(request, response);
        }
    }

}
